When a power cable needs to survive direct burial, a mine shaft, a rail tunnel, or an exposed industrial environment, the choice almost always comes down to armored cable, and specifically, to what type of armor it uses. SWA cable is the most widely specified option globally for multi-core fixed power installations, chosen for its combination of tensile strength, mechanical protection, and installation flexibility.
This guide explains what SWA cable is, how it is built, how it compares to STA and AWA alternatives, and where each type belongs.
What Is SWA Cable?
SWA stands for Steel Wire Armored, thus SWA cable means steel wire armored cable. It is a multi-core power cable protected by a layer of helically wound galvanized steel wires, positioned between the inner bedding and outer sheath. That steel wire layer absorbs mechanical impact, resists tensile pulling forces during installation, and protects the cable from external damage throughout its service life.
How Is Steel Wire Armored Cable Constructed?
From the inside out, the steel wire armored (SWA) cable has five distinct functional layers:
- Conductor: Stranded copper or aluminum, carrying the electrical load
- Insulation: XLPE (rated to 90°C) or PVC (rated to 70°C); XLPE is the modern standard for its thermal performance and resistance to aging
- Inner bedding: A layer of filler material (such as polypropylene yarn) over the assembled cores, followed by an extruded inner sheath of PVC or PE.
- Steel wire armor: Steel wire armor consists of galvanized round steel wires helically wound over the inner sheath; configurations range from single-layer wires (standard SWA) to double-layer wires (heavy-duty SWA for mines and vertical shafts). In British practice, fine wire refers to single layer; coarse wire refers to double layer or thicker wires for high mechanical stress.
- Outer sheath: PVC for standard environments; PE for burial in aggressive or wet soils; LSZH (Low Smoke Zero Halogen) for enclosed spaces where fire safety regulations apply
In AC power systems, SWA cable is always multi-core because alternating current in a single conductor creates a magnetic field, and steel, being magnetic, would form a closed loop around it, inducing eddy currents that overheat the armor. (For DC applications, single-core SWA is permissible.)
How SWA Cable Compares to STA and AWA Armor Types
Besides SWA, STA (Steel Tape Armored) and AWA (Aluminum Wire Armored) are the other two armor types commonly specified, each serving different mechanical and electrical requirements. Understanding the differences determines which armored cable belongs in your project.
| Feature | SWA (Steel Wire Armored) | STA (Steel Tape Armored) | AWA (Aluminum Wire Armored) |
| Armor material | Round galvanized steel wires | Flat galvanized steel tape | Round aluminum wires |
| Primary protection | Tensile (pulling, suspension) | Radial (crushing, compression) | Tensile, non-magnetic (Aluminum wire armor has lower tensile strength than steel wire, and reduced crush resistance.) |
| Flexibility | Good; handles tighter bends | Limited; can crack if bent | Good |
| Cable type | Multi-core only | Multi-core only | Single-core only |
| GB standard equivalent | YJV32 / YJV42 (Where IEC 60502 or equivalent national compliance is required, GENGU can supply to either GB/T 12706 or to the specified IEC standard, depending on the project’s compliance requirements.) | YJV22 | LLV/YJLV72 (subject to manufacturer’s designation; AWA is not formally standardized in GB under a single code like SWA/STA) |
| Best for | Underground runs, mines, railways, industrial trays | Direct burial with light tension; roads, buildings | Single-core MV/HV feeders |
| Relative cost | Moderate | Lower | Cost-effective for single-core |
The practical selection rule is: Use SWA wherever tensile stress matters, such as long underground pulls, vertical shafts, and industrial cable trays; use STA for straightforward direct burial where soil compression is the primary concern and installation tension is minimal; use AWA for all single-core armored applications, without exception.
Why Armored Cable Is Used
Underground power distribution presents cables with soil movement, moisture ingress, accidental excavation impact, and rodent attack simultaneously. Armored cable’s sealed multi-layer construction and mechanical strength address all of these in a single product, making it the default choice for direct burial.
Industrial facilities like petrochemical plants, steel mills, and mines expose cables to sustained mechanical hazards that unarmored cable cannot survive. Coarse wire armor variants are specified for mine shafts and vertical drops, where the cable must also bear its own suspension load.
Renewable energy sites involve long exposed cable runs across open terrain, often pulled through conduit or laid in cable trays where tensile stress is significant. Armored MV cable connects inverter stations to switchgear on solar farms and runs through wind turbine tower bases where installation tensions are high.
Rail, transit, and airport infrastructure requires cables to remain functional during a fire, not just survive physical damage. LSZH-sheathed SWA variants limit toxic fume emission in tunnels and enclosed plant rooms, where evacuation safety is a regulatory requirement.
Data center campus distribution demand both mechanical protection for backbone power runs and fire safety credentials for dense, enclosed cable environments—requirements that armored cable with LSZH sheathing meets in a single specification.
Understanding SWA Cable Naming: IEC, BS, and GB Standards Compared
SWA cable is produced under different naming conventions depending on the standard framework, and this matters in international procurement.
Under the IEC and BS framework, multi-core steel wire armored power cables are produced to IEC 60502 (extruded insulation power cables, 1kV–30kV) and to British Standard BS 5467 (thermosetting insulated armored cables, 600/1000V and 1900/3300V). The designation “SWA” is the shorthand used in these specifications and in project documentation globally.
Under China’s GB standard framework, the equivalent products carry alphanumeric codes, with digits indicating insulation type, armor type, and outer sheath material. For example, the “3” in YJV32 indicates steel wire armor, and the final “2” indicates a PVC outer sheath. Key equivalents to standard SWA cable include:
- YJV32 / YJLV32: XLPE insulated, fine steel wire armored, PVC sheathed (copper/aluminum conductor)—direct GB equivalent of standard SWA
- YJV42 / YJLV42: Coarse steel wire armored variant, for high-tension and vertical installations
- WDZA/WDZB/WDZC-YJY33 series: LSZH-sheathed variants for enclosed and fire-sensitive environments (WDZ = “halogen-free”, “low smoke”, “flame retardant”; A/B/C denotes fire retardancy class)
- ZR-YJV32 / ZR-YJV42: Flame retardant versions
- N-VV32: Fire-resistant, PVC-insulated steel wire armored cable
These products are manufactured to GB/T 12706 (extruded insulation power cables, 1kV–
35kV) and can also be produced to specified standards for international project compliance. When a specification calls for SWA cable to IEC 60502 or BS 5467, the Chinese standard YJV32 or YJV42 is the direct functional equivalent.
How GENGU CABLE Supplies SWA Armored Cable
GENGU CABLE manufactures steel wire armored power cables across low voltage (0.6/1kV) and medium voltage (up to 35kV) ratings, with copper or aluminum conductors available in both fine and coarse wire armor configurations. Beyond the standard XLPE armored range, GENGU Cable also offers LSZH-sheathed variants for transit and public infrastructure, flame-retardant and fire-resistant versions for hazardous and safety-critical installations, and low-smoke, low-halogen formulations meeting Class A/B/C fire performance requirements—a breadth of specification that most suppliers do not carry as a standard offering.
For projects specifying SWA cable to IEC 60502, BS 5467, or an equivalent national standard, GENGU’s technical team can cross-reference your specification and confirm the correct product match or discuss custom production. Contact GENGU CABLE with your project requirements and get a tailored quote.
FAQ
Can SWA cable be buried directly in the ground?
Yes. Burial depth depends on national and local regulations, and varies by voltage level, terrain, and traffic load. Always consult the applicable electrical code for your project location.
Why does single-core armored cable use AWA instead of SWA?
Steel is magnetic. A single AC conductor’s field induces eddy currents in the steel wire armor, causing it to overheat. Aluminum wire armor is non-magnetic and eliminates this problem.
What is the difference between fine wire armor and coarse wire armor?
Coarse wire armor uses larger-diameter steel wires, delivering higher tensile strength for vertical shafts, mine installations, and high suspension-load applications.
Is SWA cable the same as armored cable?
SWA is one type of armored cable. The broader category also includes STA (steel tape) and AWA (aluminum wire) variants, each suited to different mechanical and installation conditions.
